Elevator systems



June 11, 1957 v w, EAMEs 2,795,297

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mow P United States Patent ELEVATOR SYSTEMS Application August 31, 1954, Serial N 0.453314 19 Claims. (Cl. 187-29) This invention relates to elevator systems which are automatically modified to provide different modes of operation and it has particular relation to elevator systems having modes of operation which are varied with variations in service demand.

It is well known that the demand for service from an elevator system in the average building varies appreciably throughout the day. For example, during the night in an office building the elevator system usually is required to provide very little service. This period is referred to as an oft-hours period of operation.

At the start of a business day a substantial demand for service in the up direction from the lower terminal floor occurs. This period'is kown as an up-peak period. A similar period often occurs immediately following the lunch hour.

Immediately prior to the lunch hour and after the close of the business day a peak demand for down service generally is encountered. Such periods are designated down-peak periods. 1

During the remainder of the business day the demand for elevator service in the two directions of travelis substantially balanced. Such periods are known as offpeak periods.

In accordance with the invention, an elevator system is provided having a plurality of modes of operation. The mode of operation of the system is varied as a function of the demand for elevator service.

The demand for elevator service may be measuredin various ways. For example, the demand for elevator service may be determined by the number of calls for service registered in the elevator system. As a further example, the demand for elevator service may be measured by the rate of movement of loaded elevator cars in a given direction.

The invention contemplates that the response of the elevator system to the demand for elevator servicewill be modified during certain periods. Such modification conveniently may be introduced by a time switch which operates at predetermined periods of time to effect the desired changes in the response of the elevator system.

In a specific embodiment of an elevator system embodying the invention, the elevator system may be arranged to provide elevator service during the off-peak period which is substantially balanced in the two directions of travel of the elevator cars. When a predetermined demand for elevator service in a given direction is detected, the mode of operation of the elevator system is modified to expedite elevator service in such direction. Thus, if a predetermined demand for elevator service in the upward direction from the lower terminal floor is detected, the mode of operation of the elevator system is modified to expedite travel in the upward direction.

During a period in which intense upward travel is expected, the response of the elevator system to the de- I mand for elevator service may be modified to assist .in maintaining the elevator system in the mode of operation which expedites travel in the upward direction. Thus,

if an intense up peak is expected between 7:30 A.M. and 8:00 A.M., a time switch may be provided for modifying the response of the elevator system to the demand for elevator service during this period of time. For example, at 7:30, the time switch may operate to render the elevator system responsive to a smaller value of the demand for elevator service in the upward direction to convert the elevator system for up-peak operation. As a further example, the time switch may operate to increaseithe speed with which the elevator system is conditioned for up-peak operation when a predetermined demand for elevator service in the upward direction is detectedand may operate to retard the return of the elevator system to balanced operation when the demand for elevator service in the upward direction decreases.

The invention also is applicable to control the response of the elevator system to other demands for elevator systems. Thus, if a substantial demand for elevator service in the down direction is expected between 5:00 P.M. and 5:30 P.M., the system may respond to the demand for elevator service in the down direction to condition the system for down-peak operation. The operation of a time switch at 5:00 P.M. may operate to decrease the magnitude of the demand for down service to which the elevator system responds, to increase the speed with which the system is conditioned for down-peak operation or to retard the return of the elevator system to balanced or off-peak operation.

It is therefore an object of the invention to provide an improved elevator system having plural modes of operation wherein the mode of operation is responsive to the demand for elevator service and wherein such response is varied during certain periods.

It is a further object of the invention to provide an elevator system having plural modes of operation wherein the mode of operation is responsive to the demand for elevator service and wherein the elevator system responds to the demand for elevator service with a time delay which varies during predetermined periods.

Other objects of the invention will be apparent from the following description taken in' conjunction with the accompanying drawings, in which:

Figure 1 is a schematic view with circuits shown in straight-line form of a portion of an elevator system embodying the invention;

Figs. 2 to 4 are schematic views with circuits shown in straight-line form of further portions of the elevator system illustrated in Fig. 1; and

Figs. 1A to 4A, respectively, are key representations of relays and switches illustrated in Figs. 1 to 4. If Figs. 1A to 4A are horizontally aligned respectively with Figs. 1 to 4, it will be found that corresponding contacts and coils of relays and switches shown in the horizontallyaligned figures are substantially in horizontal alignment. In some cases involving groups of similar relays only representative relays are shown in the key representations.

In order to facilitate the orderly presentation of the invention, a number of conventions have been adopted. Although the invention may be incorporated in an elevator system having any desired number of elevator cars serving a structure having any desired number of floors or landings, it will be assumed that the invention is incorporated in an elevator system having three elevator cars serving a structure having six floors or landings. The elevator cars are designated by the reference supporters A, B and C. Inasmuch as the circuits associated with the three elevator cars are similar, it will suffice to show primarily the circuits associated with the elevator cars A and B. However certain components associated with the elevator car C also will be referred to.

Because of the similarity of the circuits and components associated with the three elevator cars, components as 3 sociated with the elevator cars B and C will be identified by the same reference characters employed for the components associated with the elevator car A preceded by the appropriate letter B or C. For example, the resistors R8, BR8 and CR8 are associated respectively with the elevator cars A, B and C. Consequently the discussion will be directed primarily to the elevator car A and its circuits.

Relays and switches employed for the elevator. system may have front or make contacts and back or break contacts. Front or make contacts of a relay are closed when the relay is energized and picked up. Thecontacts are open when the relay is deenergized and dropped out. Back or break contacts of a relay are closed when the relay is deenergized and dropped out. The back or break contacts are open when the relay is energized and picked up. g

Each set of contacts of a relay' or switch is designated by the reference characters employed for'the relay or switch followed by a suitable numeral specific to the set of contacts. For example, the reference characters U1 and'U3 designate the first and third sets of contacts re spectively associated with the up switch U of the elevator car A. In the drawings all relays are shown deenereized.

In order to further facilitate the presentation of the invention, certain apparatus specific to car A and certain apparatus common to all of the elevator cars are set forth as follows:

Apparatus for car A:

E-inductor slowdown relay Finductor stopping relay V--speed relay Uup switch Mrunuin g relay D-down switch Gholdin2 relay W-un preference relay Xdown preference relay 7 T--non-interference relay DRdoor relay HChi h call reversal relay ICR to 6CR--car call registering relays T-car call stoppin relay 7 SU-call-a bove relay S-floor call stopping relay 78call relay O-Guota relay SE-timed floor call stopping rela Jreversal relay Apparatus common to all cars:

IUR to URup floor call re istering relays 2BR to 6DRdown floor call registering relays HCMbank high call reversal relay DSEfirst down service demand relay EMsecond down service demand relay 2CC, 3CC. 4CC, SCC-down call quota relays 1T. 2T, 3T, 4T--timed call relays HCRsecond car-call quota relay HMCR-first car-call quota relay ZDRT to 6DRT--fioor-call timing relays USE-modifying relay PUauxiliary car-call quota relay PUAauXiliary down call quota relay PUT-first timing relay DOT-second timing relay PUTAthird timing relay DOTAfourth timing relay CLtiming switch Figure 1 Fig. 1 shows the elevator cars A and B and certain control circuits associated therewith. The elevator car A will be assumed to be stopped at the second floor of the structure whereas the elevator car B will be assumed to be stopped at the fifth floor of the structure. With these exceptions, the circuits and mechanisms associated with the two elevator cars are similar and will be understood by reference to those associated with the elevator car A. Circuits for the elevator A are shown in the left-hand column in Fig. 1.

The elevator car A is connected by a rope or cable 10 to a counterweight 11. The rope 10 passes over a sheave 12, which is secured to a shaft 13 for rotation therewith. The shaft 13 is rotated by a motor 14 which may be of any conventional type. For present purposes it will be assumed that the motor 14 is a direct current motor having its armature 14A secured to the shaft 13 and having a field winding 14F which is permanently connected across two direct-current buses L1 and L2 which supply direct current energy for the control circuits.

The elevator car A has therein a plurality of normallyopen car-call push buttons 1c to 6c which are actuated for the purpose of registering calls respectively for the first to sixth floors as desired by passengers entering the elevator car.

To permit registration of calls for service by prospective passengers located at the various floors served by the elevator cars, push button stations are located at such floors. Such a station is shown in Fig. 1 for the third floor. It includes a normally-open up floor call push button 3U which is pressed by a prospective passenger desiring elevator service in the up direction. A similar push button is located at each floor from which service in the up direction may be desired. The station also includes a normally-open push button 3D which is pressed by a prospective passenger desiring elevator service in the down;direction. A similar push button is located at each floor from which elevator service in thedown direction may be desired. The numeral of the reference characters (as 3D or 3U) indicates the floor at which the push button is located.

The elevator car A also has mounted thereon a slowdown inductor relay E and a stopping inductor F which may be of conventional construction. The slowdown relay E has two sets of break contacts E1 and E2 associated therewith. The relay has a normally incomplete magnetic circuit and initial energization of the winding of the relay alone does not initially open the associated contacts. However, if the slowdown relay E reaches an inductor plate UEP located in the hoistway of the elevator car while the winding of the relay is energized, the contacts E1 open. The inductor relay may be of the type which when it opens the contacts maintains the contacts open until the relay winding is deenergized even though the relay passes beyond the inductor plate. In Fig. l the inductor plate UEP is assumed to be mounted in the hoistway to be reached by the slowdown relay E as the elevator car A nears the third floor. If the elevator car A is to stop at the third floor, the winding of the relay E-is energized and when the relay reaches the inductor plate UEP for the third floor, the contacts E1 open to initiate a slowdown operation for the elevator car. It will be understood that a similar inductor plate is similarly associated with each of the floors at which the elevator car A may stop during up travel thereof.

During down travel of the elevator car A, the inductor relay E cooperates with down inductor plates DEP to initiate a slowdownof the elevator car as it approaches a floor at which the elevator car is intended to stop. For

-example, if the elevator car is to stop during down travel at the third floor, the winding of the inductor relay E is energized as the elevator car nears the third floor. When the inductor relay reaches the down inductor plate DEP for the third floor, the contacts E2 open to initiate a slowdown operation of the elevator car. It will be understood that a similar inductor plate DEP is pro vided for each ofthe floors at which the elevator car A is to stop during down travel thereof.

The stopping relay F similarly cooperates with inductor plates UFP and DFP for the purpose of bringing the elevator car to a stop as it reaches a floor at which it is to stop. Thus, if the elevator car A during up travel is to stop at the third floor, the winding of the stopping relay F is energized and as the inductor relay of stopping relay F reaches the stopping inductor plate UFP for the third floor, the contacts F1 open. These contacts in opening result in stopping of the elevator car at the third floor. A similar inductor plate is provided at each of the floors for which the elevator car A is to stop during up travel thereof.

If the elevator car A is to stop at the third floor during down travel thereof the winding of the stopping relay is energized and as the relay reaches the inductor plate DFP for the third fioor, the contacts F2 open to produce a stopping operation of the elevator car at the third floor. It will be understood that a similar inductor plate is provided for each of the floors at which the elevator car A is to stop during down travel thereof.

Because of the large number of control circuits required, it is conventional practice to provide each elevator car with a floor selector 16. This selector includes a plurality of rows of contact segments mounted on the insulating panel 16A. Only two rows of contact segments al to a5 and all to d5 are illustrated in Fig. 1. These contact segments are successively engaged during travel of the elevator car respectively by brushes aa and dd for the purpose of controlling the energizations of certain circuits. For example, if the elevator car A during down travel is to stop at the third fioor in response to a car call, the brush aa engages the contact a3 shortly before the elevator car A reaches the third floor, to initiate a stopping operation thereof.

The brushes aa and dd are mounted on a brush carriage 16C which is mounted for movement in accordance with movement of the elevator car, but at a greatly reduced rate. In the embodiment of Fig. 1, it is assumed that the carriage 16C has threaded engagement with a screw 165 which is coupled to the shaft 13 through suitable gearing for rotation in accordance with movement of the elevator A. Consequently, as the elevator car A moves, the brushes mounted on the carriage 16C permit the energization of appropriate circuits at various points of travel of the elevator car.

Although the driving motor 14 may be energized in various ways, it will be assumed that the control of this motor is of the type commonly referred to as a variable voltage control. In such a control, a direct current generator 17 has its armature 17A connected in a loop with the armature 14A of the motor. A series field winding 17$ for the generator also may be included in this loop. The generator has a main field winding 17F which is connected for energization from the buses L1 and L2 through a reversing switch. This reversing switch in cludes contacts U2 and U3 of an up switch. When these contacts are closed, the field winding is energized with proper polarity for up travel of the elevator car. On the other hand, when contacts D2 and D3 of a down switch are closed, the field winding is energized with proper polarity for down travel of the elevator car. The energization of the field windings is completed through a resistor R1 for slow speed operation of the elevator car or through make contacts V1 of a speed relay for full speed operation of the elevator car.

The elevator car A is provided with a conventional spring-applied electromagnetically-released brake. This brake includes a brake drum 18D which is secured to the shaft 13 for rotation therewith. A brake shoe 13C normally is biased against the brake drum by means of a spring (not shown). The brake is released upon energization of a brake coil 18B which cooperates with a magnetic armature 18A secured to the shoe 18C. The coil 18B is connected to the buses L1 and L2 for energization either through make contacts U1 or through 6 make contactsDl of the up switch U or the down switch D.

The speed relay V is connected for energization from the buses L1 and L2 through either of two paths. One of these paths includes make contacts U4 of the up switch, a limit switch 19 and the break contacts E1 of the slowdown relay. The limit switch 19 .is a cam-operated normally-closed switch which is opened as the elevator car nears its upper limit of travel.

The remaining path of energization comprises the make contacts D4 of the down switch, a limit switch 20 and the break contact E2 of the slowdown relay. The limit switch 20 may be cam operated. It is normally closed and is opened as the elevator car A nears its lower limit of travel.

As long as the elevator car A is running, the running relay M is energized. This relay can be energized only as long as the make contacts DR1 of a door relay DR are closed. These contacts are closed only as long as all of the hoistway doors and car doors for the car A are closed. Such safety provisions are well known in the art.

The running relay M initially can be energized only if the break contacts 78-1 are closed to indicate that a call for service has been registered and if the break cont-acts T1 are closed to indicate that sufficient time has elapsed since the last stop of elevator car A to permit discharge or entry of passengers.

Assuming that the foregoing contacts associated with the running relay M are closed, the relay may be energized initially through either of two paths. One of these paths is as follows:

L1, 70T1, 78-1, W1, F1, 21, U, M, DR1, L2

Since the up switch U is energized through this path, it follows that the elevator car will be conditioned for up travel. The limit switch 21 is a normally-closed mechanically-operated switch which is opened as the elevator car A nears its upper limit of travel. When energized, the up switch U closes its make contacts US to establish a holding circuit around the contacts 70T1, 78-1 and WI.

The second path for initially energizing the running relay M maybe traced as follows:

L1, 7011, 78-1, X1, F2, 22, D, M, DR1, L2

Since the down switch D now is energized, it follows that the elevator car A is conditioned for down travel. The limit switch 22 is a mechanically-operated normally-closed switch which is opened as the elevator car A nears its lower limit of travel. When it picks up, the down switch D closes its make contacts D5 to establish a holding circuit around the contacts 70T1, 7 8-1 and X1.

If the elevator car A is to be operated by a car attendant the contacts 78-1 and 70T1 may be replaced by a manually-operated switch which is closed by the car attendant when the car is to be moved from a floor at which it is stopped. However in a preferred embodiment of the invention the automatically'operated contacts 78-1 and '7 TF1 are employed.

The slowdown relay E, the inductor relay F, and a holding relay G are energized in parallel from the buses L1 and L2 through make contacts M1 of the running relay M. To complete an energizing circuit for these relays E, F and G, one of the following conditions must be present: First, the make contacts T1 are closed to indicate that a car call is registered for a floor which the elevator car A is approaching. Second, the contacts 11 are closed to indicate that the elevator car A is conditioned to reverse at the next floor reached by the elevator car. Third, the make contacts S1 are closed to indicate that the elevator car A is conditioned to stop at a floor in answer to a registered floor call for such floor. Fourth, the contacts SE1 are closed to indicate that the elevator car A is approaching a floor for which a priority floor call has been registered for a long period of time.

When the holding relay G is energized, it closes its floor in its direction of travel.

7 make contacts G1 to establish with the make contact M1 a holding circuit for the inductor relays E and F.

The direction of travel of the elevator car A is determined'initially by an up preference relay W and a down preference relay X. For the up preference relay W to be energized, the break contacts D6 must be closed (i. e. the

down switch D is energized). The break contacts X2 must be closed (i. e. the down preference relay X is deenergized). The limit switch 23 also must be closed. This switch is normally closed and is opened as the elevator car A reaches its upper limit of travel, in this case, the sixth floor.

Energization of the up preference relay W also requires closure of at least one of two sets of contacts. These include the break contacts I 2 which are closed when the elevator car A is not conditioned to reverse at the nearest Make contacts M2 are closed as long as the elevator car A is running.

The down preference relay X is energized if the break cont-acts U6 are closed (i. e. the up switch U is deenergized), the break contacts W2 are closed (i. e. the up preference relay is deenergized) and the limit switch 24 is closed. This limit switch is normally closed and is opened as the elevator car A reaches the lower terminal vfloor.

As long as the elevator car A is running, the make contacts M3 are closed to energize the non-interference relay 70T. When the elevator car A stops, the contacts M3 open to deenergize the relay. However, the relay 70T has a substantial delay in dropout. This delay may be provided in any suitable manner as by connecting a resistor R2 across the relay coil. The time delay in dropout is selected to be sufiicient to permit discharge of passengers from the elevator car A or entry of passengers into the elevator car A after each stop.

It will be recalled that door relay DR is connected across the buses L1 and L2 through contacts operated by each door associated with the elevator car A. If any of the doors is open, the contacts associated therewith are also open to prevent energization of the door relay DR.

Energizati-on of the high call reversal relay J prepares the elevator car A to reverse during up travel at the nearest floor. The high call reversal relay I may be energized if the elevator car A is conditioned for up travel (break contacts X3 are closed) and if certain other conditions are satisfied.

Thus, if at least a predetermined number of priority down floor calls are registered, make contacts 1T1 are closed. If at least a predetermined number of down floor calls are registered, make contacts 2CO1 are closed, or if at least a predetermined number of car calls are registered for the system, the make cont-acts MHORI are closed. If in addition to one of these closures the make contacts 78U1 are closed to indicate no higher calls remain to be answered (in some cases no higher car calls), the energizing circuit for the reversal relay I may be completed.

Figure 2 Figure 2 shows the call registration circuits for the elevator cars. Car call registration circuits are illustrated for the elevator cars A and B in the upper part of this figure.

It will be recalled that the elevator car A is provided with a plurality of push buttons 10 to 6c for the purpose of registering car calls. Inasmuch as car call push buttons and associated circuits for the intermediate floors are similar, they are not illustrated in Fig. 2 for the third and fourth floors. Each of these push buttons has associated therewith a car call registering relay ICR to 6CR respectively. In this group only representative relays 6CR, ZCR and ICR are shown in Figs. 2A and 3A. The push buttons and call registration relays cooperate with four rows of contact segments located on the floor 'selector for the elevator car A. The contact segments al to a cooperate with the brush aa for the purpose of initiating a stopping operation of the elevator car during down travel of the elevator car respectively at the first to fifth floors. The contact segments b2 to b6 cooperate with a brush bb for the purpose of initiating a stopping operation of the elevator car during up travel of the elevator car respectively at the second to sixth floors. A brush cc cooperates with a row of contact segments c2 to 06 and a brush'dd cooperates with a row of contact segments d1 to d5 for the purpose of cancelling registered carcalls as they are answered respectively during down travel and up travel of the elevator car. It will be understood that for each contact segment, the numeral of the reference character designates the floor with which the contact segment is associated. Thus, the reference character a1 designates the contact segment for the first floor in the a row.

By reference to Fig. 2, it will be observed that when the car call push button 50 is pressed the car call registering relay 5CR is connected therethrough across the buses L1 and L2. This relay closes its make contacts 5CR1 to establish a holding circuit around the push button. The contact segments a5 and b5 are connected through this setof contacts to the bus L1.

If the elevator car A is set for down travel, the make contacts X4 are closed. And if the elevator car is approaching the fifth floor, the make contacts M4 of the running relay also are closed. Consequently, as the elevator car nears the fifth floor, the brush aa engages the contact segment a5 to complete the following circuit for the car call topping relay T:

L1, 5CR1, a5, aa, X4, T, M4, L2

The energization of the relay T initiates a stopping operation of the elevator car A at the fifth floor.

As the elevator car A continues its approach toward the fifth floor, the contact segment c5 is engaged by the brush cc. As the elevator car comes to a stop, the break contacts MS of the running relay close to complete the following cancelling circuit:

L1, 5CR1, SCRN, 05, cc, X5, M5, L2

The operating coil of the registering relay SCR and the cancelling coil SCRN are wound in opposition on a common core. Consequently, energization of the cancelling coil SCRN cancels the effect of the operating coil and resets the registering relay SCR. Preferably, as the elevator car stops at the fifth floor, the brush aa passes slightly below the associated contact segment a5, how ever, the brush cc remains in engagement with the associated contact segment 05 as long as the elevator car A remain at the floor.

Next it will be assumed that the same call is registered for the fifth floor as the elevator car A travels up towards the fifth floor. Under these circumstances, the make contacts W3 and W4 of the up preference relay are closed. As the elevator car A nears the fifth floor, the brush bb engages the contact segment b5 to complete the following circuit:

L1, 5CR1, b5, bb, W3, T, M4, L2

The energization of the car call stopping relay T results in the initiation of a stopping operation for the fifth floor.

As the elevator car A continues to approach the fifth floor, the brush dd engages the contact segment d5 to complete the following circuit:

L1, 5CR1, SCRN, d5, dd, W4, M5, L2

The energization of the cancelling coil SCRN resets the call registering relay SCR. During the stopping operation, the brush bb preferably passes slightly above the associated contact segment b5 whereas the brush dd remains in engagement with the associated contact segment d5 as long as the elevator car A is at the fifth floor.

The car call registering circuits for all of the intermediate floors are similar to those described for the fifth floor. For this reason and to conserve space, the inter a and d rows.

mediate floor circuits are illustrated in Fig. 2 only for the second and fifth floors.

The car call registering circuits for the upper terminal (sixth floor) may be similar to those employed for the intermediate fioors. However, since the elevator car A stops at the sixth floor only during up travel, contact segmentsfor the sixth floor need not be provided in the By reference to Fig. 2 it will be noted that only contact segments [16 and 06 are provided for the sixth floor.

The car call registering circuits for the lower terminal or first floor may be similar to those provided for the intermediate floors. Since the elevator car stops at the first floor only during down travel, contact segments for the first floor need not be provided in the b and rows. For this reason, in the car call registering circuits only contact segments a1 and d1 are illustrated for the first floor.

The central part of Fig. 2 illustrates up floor call registering circuits. These circuits are operated by means of normally-open push buttons 1U to U common to all of the elevator cars which are located respectively at the first to fifth floors. Inasmuch as the push buttons and associated circuits for the intermediate floors are similar, theyare not shown for the third and fourth floors. The push buttons have associated therewith up floor call registering relays lUR to SUR and cancelling coils lURN to SURN in a manner which will be clear from the discussion of the call registering relays and cancelling coils associated with the car call push buttons.

The up floor call registering relays lUR to SUR and their cancelling coils are associated with contact segments for each of the elevator cars in the bank. For example, a row of contact segments e1 to 26, respectively for the first to sixth floors, is provided for the elevator car A and cooperate with a brush ee. A brush ff cooperates with a row of contact segments 1 to f5, respectively for the first to fifth floors for the elevator car A.

Let it be assumed that while the elevator car A is traveling up a prospective passenger waiting on the fifth floor presses the up floor call push button 5U to energize the up fioor call registering relay SUR. This relay closes its make contact SURl to establish a holding circuit around the push button.

Since the elevator car is assumed to be travelling up, the make contacts W5 of the up preference relay W are closed. It will be assumed further that the break contacts MHCR3 (Fig. 2) of the first car-call quota relay MHCR are closed. (Although the elevator car B may employ similar contacts of the relay MHCR, in the embodiment illustrate-d the elevator car B does not employ such contacts but instead employs in the corresponding circuit break contacts HCRl of a second car-call quota relay HCR. In addition, the elevator car B circuit includes break contacts 3CC1 of a down call quota relay 3CC and break contacts 2T1 of a timed call relay 2T.) It is assumed that break contacts EM1 of the second down service demand relay EM are closed. As the elevator car A nears the fifth floor, the brush ee engages the contact segment 25 to complete the following circuit:

L1, 5UR1, e5, ee, W5, MHCRI), S, EM1, L2

The energization of the floor call stopping relay S initiates the stop at the fifth floor. Inresponse to movement of the car towards the fifth floor, the brush ff engages its contact segment f5. As slow down of the elevator car is initiated, the break contacts V6 close to complete the following cancelling circuit:

L1, 5UR1, SURN, f5, ff, W6, V2, L2

This resets the up floor car registering relay SUR. As the elevator car A comes to a stop, the brush ee preferably passes slightly above the contact segment e5. However, the brush ff remains in engagement with the contact segment f5 as long as the elevator car A remains at the fifth floor. By inspection of Fig. 2, it will be observed that the eontact segment e5 is connected to the eerie spending contact segments for the other elevator cars in the bank (such as contact segment B25 for the elevator car B). Similarly, the contact segment f5 is connected to corresponding contact segments (such as the contact segment M5) for the remaining cars of the bank. Consequently, operation of the push button 5U is effective to-stop the first up traveling elevator car which reaches the fifth floor and which is conditioned to accept the call at the fifth floor.

The up floor call registering circuits for all of the intermediate floors are similar. Consequently, such circuits are illustrated in Fig. 2 only for the second and fifth'floors.

During up travel, the elevator cars also stop at the sixth floor if they reach such floor. For this reason, a single contactsegment e6 sufiices for the sixth floor and is permanently connected to the bus L1. Since the elevator car A does not stop during up travel at the lower terminal or first floor, a contact segment in the e row is not required. With this exception, the call registering circuits for the first floor are similar to those described for the fifth floor.

The lower part of Fig. 2 illustrates the down floor call registering circuit for the elevator cars. Down floor calls are registered by operation of normally-open push buttons 2D to 6D for the second to sixth floors, respectively which have associated therewith down floor call registering relays ZDR to 6DR and cancelling coils ZDRN to 6DRN. Each push button cooperates with its call registering relay and its cancelling coil in the manner discussed with reference to the up floor call push buttons. Only relays 2DR, 3DR and 6DR in this group are shown in Figs. 2A, 3A and 4A.

For the-elevator car A, ,a row of contact segments g1 to g5 cooperates with a brush gg and a row of contact segments 112 to I16 cooperates with a brush hh. Let it be assumed that the elevator car A while traveling down is approaching the fifth floor at which a down floor call has beenregistered by operation of the push button 5D. Such operation results in energization of the down floor call registering relay SDR to close the make contacts SDRl. Since the elevator car is traveling down, the make contacts X6 and X7 are closed. It will be assumed that break'contacts HCR3 and EM1 are closed.

As the elevator car A nears the fifth floor, the brush g g engagesthe contact segment g5 to complete the following circuit:

L1, SDRl, g5, gg, HCR3, X6, S, EM1, L2

The energization of the floor call stop relay S initiates a stopping operation of the elevator car A at the fifth floor. As the elevator car continues its approach, a brush hhengages the contact segment $15. The initiation of slow down of theelevator car A results in closure of the break contacts V2 to complete the following cancelling circuit:

L1, 5on1, SDRN, hs, hh, X7, v2, L2

The energization of the cancelling coil resets the call registering relay SDR. Preferably, as the elevator car A comes to astop, the brush gg passes slightly below the associated contact segment g5, but the brush hh remains in engagement with the associated contact segment h5.

The contact segment 35 is connected to corresponding contact segments (such as the contact segment Bg5) of the remaining cars. Similarly, the contact segment h5 is connected to the corresponding contact segments (such as the contact segment Bh5) for the remaining cars. Consequently, the first elevator car to approach the fifth floor while traveling down will answer a call registered by the call registering relay 5DR.

The down floor call registering circuits for all of the intermediate floors are similar and may be traced readily in Fig. 2. The down floor call registering relays for the upper terminator sixth floor also may be similar. Howsively by the brush kk as the elevator car A moves.

.ever, since the elevator car A does not stop at the sixth floor during down travel, the contact segment in the g row may be omitted for the sixth floor.

.. the contacts EMl.

In Fig. 3, a call circuit 30 for car A is provided which has two functions. This circuit energizes a call relay 78 when no call is registered in the elevator by the car call push buttons for the elevator car A or by any floor call push button. In addition, the call circuit 30 energizes the call above relay 78U as the elevator car during up travel nears the highest floor for which a down floor call on a car call is registered provided no up floor call is registered for such floor or a higher floor.

The call-above circuit 30 includes break contacts for all of the floor call registering relays and for all of the elevator A car call registering relays arranged in the order of the floors. This circuit may be traced as follows:

L1, 6CR2, 6DR2, UR2, 5CR2, 5DR2, 4UR2, 4CR2, 4DR2, 3UR2, 3CR2, 3DR2, 2UR2, 2DR2, 2CR2, 1CR2, 1UR2, 78, L2

By inspection of this circuit, it will be observed that as long as a call is registered by the car call push buttons for the elevator car A or by the floor call push buttons the relay 78 is deenergized.

The call circuit 30 has associated therewith a row of contact segments k1 to k5 which are engaged succes- The contact segments are so located relative to the call circuit 30 that each contact segment is placed below all break contacts of the call circuit which require travel of the elevator car A above such contact segments. Thus, the contact segment k5 is connected to the call circuit between the contacts 5UR2 and 5CR2. The contact segment k4 is connected between the contacts 4UR2 and 4CR2. The location of the remaining contact segments similarly may be ascertained by reference to Fig. 3. It will be noted that the relay 78U is connected between the brush kk and the bus L2 through make contacts W7 of the up preference relay W.

In certain cases, it is desirable to prevent registered calls from affecting the call circuit 30. For example, it may be desirable under some conditions to prevent registered floor calls from affecting the operation of the relay 78U and 78. To this end, make contacts of the first-car-call quota relay MHCR are provided for the purpose of shunting the break contacts of the floor call relays. When the relay MHCR is energized, the contacts MHCR4 to MHCRS close to shunt contacts 5UR2 to 2UR2 and 6DR2 to 2DR2.

Although contacts of the relay MHCR similarly may be associated with the call circuit B30 for the elevator car B, in a preferred embodiment of the invention a separate relay HCR has make contacts I-ICR4 to HCRS associated with the call circuit B30 to shunt contacts 5UR3 to 2UR3 and 6DR3 to 2DR3, as clearly shown in Fig. 3.

Make contacts EM3 to EM6 and USEl to USE4 are arranged to shunt contacts of the up floor call registering relays in the call circuits 30 and B30 for floors above the first floor.

The down call quota relays 2CC to SCC indicate the presence of predetermined service demands. in Fig. 3, the quota relays and a relay PUA preferably are energized in accordance with the number of registered down floor calls. The energization of the relays is dependent on the condition of a parallel circuit having ,fiv e parallel arms. Each arm contains a -suitable re- As showndiscussed.

. time switch.

sistor and a set of make contacts of a separate one of the down floor call registering relays. The resistors are so proportioned that a predetermined number of down floor calls must be registered before the relays will pick up. A switch SW6 controls in part the energization of the relay 20C. For the present it will be assumed that the switch SW6 connects the relay 2CC in series with the relays 3CC to SCC.

The number of calls to which the down call quota relays respond depends on the number of floors of the elevator system, the number of elevator cars and other factors of the particular installation. For present purposes it will sufiice to assume that the relays 2CC, 3CC, 4CC and 5CC pick up respectively in response to registration of two, three, four and five down floor calls. A resistor R24 may be provided for controlling the sensi tivity of the relay 5CC.

The circuits of Fig. 3 which have thus far been described specifically are for the purpose of providing various modes of operation which are selected at all times in accordance with the demand for elevator service. As previously pointed out, it is desirable in many elevator systems to modify the response of the elevator system to the demand for elevator service during certain periods. Such variation in response is provided by the circuits in Fig. 3, which now will be described.

Let it be assumed that the switch SW6 is operated to its lower position as illustrated in Fig. 3 wherein a shunt is established across the poles or blades of the switch. Under such circumstances, the relays 3CC, 4CC, 5CC are connected for energization in the manner previously It will be noted that the auxiliary down call quota relay PUA also is connected in series with the relays 3CC to SCC. This relay may be designed to pick up when energized in response to registration of a predetermined number of down floor calls, such as two calls.

The relay PUA cooperates with circuits which are placed in effective condition by closure of a switch SW1. At the same time, the switch SW5 is closed to connect the relay 2CC for energization through the break contacts PUTAI and the switch SW1.

The closure of the switch SW1 energizes the third timing relay PUTA through the break contacts PUAl. The relay PUTA has a time delay in dropout which is controlled by the eifective resistance of a resistor R20. A decrease in effective resistance increases the time delay. The etfective value of this resistor may be reduced by closure of the contacts CLZ of a time switch. For present purposes, it will be assumed that these contacts open during periods of the day when intense demand for down peak service is anticipated.

The relay PUA has make contacts PUA2 which control the energization through the switch SW1 of the fourth timing relay DOTA. This timing relay has a time delay in dropout which is determined by the effective resistance of a resistor R21. The effective resistance of this resistor is reduced by closure of the contacts CL1 of the It will be assumed that the contacts CLl are closed only when the contacts GL2 are open.

When the relay 2CC picks up, it closes make contacts 2CC4 which partially establish a self-holding circuit for the relay. The holding circuit also includes make contacts DOTAl of the fourth timing relay DOTA. It will be understood that the relay 2CC also operates its previously discussed contacts.

Figure 4 The timed call relays 1T, 2T, ST and 4T compute the number of registered down floor calls which have been registered for more than a predetermined time. To this end the relays are energized through a parallel circuit having five parallel arms. Each of the arms includes a set of break contacts 2DRT1 to 6DRT1. These contacts close respectively when down floor calls have been registered respectively at the second to sixth floors for more than a predetermined time.

in the demand for down service.

shame? The resistors RTl to RT in the parallel cir'cuit and the timed call relays IT to 4T are so selected that each of the time call relays picks up in response to registration of at least a predetermined time. For present purposes, it will sufli'ce to' assume that the relay 1T picks up if one or more down floor calls has been'registe e'd for more than the predeterinine-d time. The relay 2T picks up onl if it is energized through two' or more of the resisters RTl to RTS to indicate that two or more timed out or priority down floor calls are registered. In an analogous manner the relays 3T and 4T pick up in response to the presence of at least respectively three and four timed out or priority down floor calls.

The down @2111 quota relays 20C to 5CC (Fig. 3) and the timed call relays IT to 4T (Fig. 4) are employed for computing the demand for elvato'r'service in the down directionandfor controlling the bperation of the elevator system in accordance with such demand. It will be ecalled that closure or the make contacts 1T1 or 2CC1 (Fig; 1) prepares the reversal'relay J for energization as the elevator car A when traveling up approaches the farthest floor for which a callisregistered provided such call is not an up floor call. In Fig. 2 opening of either the break contacts 2T1 or the break contacts SCCI prevents response of the elevator B to up floor calls. In Fig. 3 closure of the make contacts 2T2 or 3CC2 energizes the modifying relay USE.

The pickup of the down call ueta, relay 4CC or of the timed call relay 3T indicates a still further increase The pickup or either of these relays is accompanied by closure of the make contacts 4C C1 or 3T1 to energize the'first down service relay DSE (Fig. 3). The energization of this relay may increase the capacity of the elevator system to handle down traflic in a known manner, as'by dividing the floois into zones or groups each served by a separate group of elevator cars.

I A still further increase in the demandfor down service 'is accompanied by pickup ofthe'down "call quota relay SCC or of the timed call relay Pickup of either of these relays is accompanied by'closure of the make contacts 5061 or 4T1 toenergize a second down service demand relay EM. Pickup of this relay results in opening of the break contacts EMI (Fig. 2) and similar contacts for the other elevator cars of the system to prevent 'energization of the floor call stopping relays. As willbe pointed out in the discussion of Fig. 4, during the energization of the second down service demand relay EM the elevator cars can respond to down floor calls only if such calls have been registered for more than a predetermined time.

The performance of the elevator system also'is controlled by the first car call quota relay MHCR (Fig. 4)

and the second car call quota relay HGR. These relays are connected in series with each other, when the switch SW3 is in the position illustrated, and 'in series with break contacts 2CC3 and 1T3 and a relay PU for energization through a parallel circuit containing 'a plurality of arms. Each of the arms includes a set of make contacts of a separate one of the car call registering relays and a resistor. In order to conserve space only two arms are' illustrated for each of the elevator cars A, B and C. Thus for the elevator car A one of the arms contains break contacts 1CR3 and a resistor R8. A second arm contains break contacts 6CR3 and a'resistor R13.

It will be understood that a similar arm is provided for each of the car call registering relays associated with each of the elevator cars.

The first car-call quota relay MHCR is designed to-pick up when energized through at least apredetermincd number of the parallel arms of its energizing circuit. For present purposes it Will be assumed that this relay is picked up only if energized through at least three arms of the parallel circuit.

The second carcall quota relay HCR-is designed to pickup when energized through a larger number of arms ofthe parallel Cifilit. For the pUIpOSe Of discussion it will be assumed that this relay is designed to pick up only if energized by at least six arms of the parallel circuit. The pickup point of'either of the relays "may be adjusted in any suitable manner as by connecting an adjustable resistor thereacross. As a specific example, an adjustable resistor RH is illustrated in parallel with the second car call quota relay HCR.

If desired, each of the parallel arms through which the relays HCR and MHCR are energized may include make contacts ofthe up preference relay for the associated elevator car. If such an expedient is adopted, the relays are energized in accordance with the number of car calls registered by passengersdesiring to travel in the up direction. However, for present purposes it will be assumed that such contacts of up preference relays are not employed.

A modified operation during up-peak periods may be obtained by operating the switch SW3 -to its upward position, as viewed inFig. '4, wherein the poles or blades of the switch are shunted. In addition, switch SW4 is closed to connect the relay MHCR for energiza'tion through the break contacts PUTI, 1T3 and 2CC3;

The relay PU is counec'te'd'inseries with the relay HCR and is designed to pick up when energized through a predetermined number of arms of the associatedparallel circuit. For present purposes, it will be assumed that this relay picks up when energized through three or more of the arms, If the switch SW2 is closed, the first timing relay PUT is energized through the break contacts PUl, IT3 and 2CC3. This relay has a time delay in dropout whichis determined the efie'c'tive value of the resistor R22. The resistor has its resistance reduced by closure of the contacts CL4 of a time switch. These contacts will he assumed to be open during periods when an intense demand for elevator service in the up direction cfie'ctive value 'of the resistor R23. The effective value of resistance of this resistor isincreased by opening of the contacts CLS of'th'e time switch which are assumed to be closed when the contacts GL4 are open. Pickup of the relay -DOT closes make contacts -DOT1 to complete with the make contacts MHCR9 a holding circuit around the contacts PUTl.

The 'floor call timing relays ZDRT to 6DRT are employed for the purpose of measuring the duration of registration 'of each down floor call. For example, the fioor call timing relay 2DRT for the second floor is connected across the huses L1 and L2 through break contacts 2DR5 of the down floor call registering relay ZDR for the second floor. When a down floor call is registered for the second floor the break contacts '2DR open to deenergize the floor call timing relay ZDRT. This relay has a substantial time delay in dropout. This time delay may be provided in any suitable manner. For purposes of illustration it will be assumed that a resistor 2R7 is connected across the relay for the purpose of delaying its dropout. For present purposes it will be assumed that the delay in dropout of the relay is of the order of 40 seconds. Each of the remaining floor call timing relays 3DRT to 6DRT similarly is associated with break contacts of the down floor call registering'relay for the associated floor.

It will be recalled that break contacts 2DRT1 to 6DRT1 of the floor call timing relays control the energization of the timed call relays IT to 4T (Fig. 3). In addition, the floor call timing relays have break contacts 2DRT2 to 5DRT2 (Fig. 4) which are employed for the purpose of controlling the energizati'on of a timed floor call stopping By inspection of Fig. 4 it will be noted that the elevator car A is provided with a row of contact segments n2 to n which may be mounted on the floor selector for the elevator car A. Each of these contact segments is connected to a similar contact segment for each remaining elevator car of the system. A brush nn is associated with the row of contact segments for the elevator car A. As the elevator car A moves from the sixth floor to the lower terminal floor, the brush nn successively engages the contact segment n5 to n2 as the elevator car approaches respectively the fifth to second floors.

Each of the contact segments such as n2 is connected to a conductor LC through break contacts such as 2DRT2 of the floor call timing relay associated with the same floor. The brush rm is connected to the bus DC- through the timed floor call stopping relay SE and make contacts X8 of the down preference relay X. The conductor LC is connected to the bus L1 through make contacts EM11. Consequently, if the contacts EM11 are closed and the elevator car A is traveling in the down direction, the timed floor call stopping relay SE will be energized as the elevator car A approaches each floor for which a down floor call has been registered for more than a predetermined time.

Operation In order to assure a full understanding of the invention, certain typical operations of the elevator system now will be considered. First, it will be assumed that the elevator cars are parked at the lower terminal floor and that a passenger enters the elevator car A at the lower terminal floor for the purpose of proceeding to the fifth floor.

The doors of the elevator cars may be of the manuallyopened, spring-closed type or may be of conventional power-operated design. Upon entering the elevator car A, the passenger presses the car call push button 50 (Fig. 2) to energize the associated car call registering relay 5CR. This relay closes its make contacts 5CR1 to establish a holding circuit around the push button. The relay also opens its break contacts 5CR2 (Fig. 3) to deenergize the relays 78U and 78. Inasmuch as the elevator car A is at the lower terminal floor, it will be understood that the up preference relay W is energized and picked up.

The car call registeringrelay also closes its make contact 5CR3 (not shown in Fig. 3 but similar to 6CR3). However, it will be recalled that the energization of the relays MHCR and HCR through a single one of the resistors R8 to R13 is insufficient to pick up either relay.

Inasmuch as the relay 78 is now dropped out, the contacts 78-1 (Fig. 1) are closed. .It will be assumed also that the elevator car A has remained at the lower terminal floor for a time sufiicient to result in closure of the break contacts 70T1. Consequently, upon closure of the doors, the door relay DR closes its make contacts DRl to complete the following circuit:

L1, 70T1, 78-1, W1, F1, 21, U, M, DRl, L2

Upon energization, the up switch U closes its make contacts U1 to release the elevator brake. Contacts U2 and U3 close to energize the generator field winding 17F with proper polarity for up travel of the elevator car. Contacts U4 close to completethe following energizing circuit for the speed relay V:

L1, U4, 19, E1, V, L2

The speed relay closes its make contacts V1 to shunt the resistor R1 and conditions the elevator car for full speed operation. The speed relay V also opens its break contacts V2 (Fig. 2) without immediate effect on the system operation.

Continuing with the operation of the up switch U, the energized up switch closes its make contacts US to establish a holding circuit around the contacts 70T1, 78-1 and W1. Break contacts U6 open to prevent energization therethrough of the down preference relay X.

The elevator car A now accelerates in the up direc- 'tion for the purpose of carrying the passenger to the fifth It will be recalled that the running relay M also was energized. As a. result of its energization, the running relay closes its make contacts to prepare the relays G, E and F for subsequent energization. The make contacts M2 close to maintain the energization of the up preference relay despite subsequent opening of the break contacts J2. Make contacts M3 close to energize the non-interference relay 70T. The non-interference relay opens its break contacts 70T1 but such opening has no immediate effect on the operation of the system.

Referring to Fig. 2, the running relay M closes its make contacts M4 and opens its break contacts M5. Such contact operations have no immediate eflfect on the operation of the system.

As the elevator car nears the fifth floor, the brush kk (Fig. 3) engages the contact segment k5 which is positioned above the open break contacts 5CR2. Consequently, the call-above relay 78U is energized through the circuit:

The relay 78U closes its make contacts 78U (Fig. 1). Under the assumed conditions, the energization of the vrelay 78U has no immediate effect on the operation of L1, 5CR1, B5, bb, W3, T, M4, L2

The car call stopping relay closes its make contacts T1 (Fig. 1) to energize through the contact M1 the three relays G, E and F in parallel. The relay G closes its make contacts G1 to establish a holding circuit around the contacts T1.

The energization of the inductor slowdown and stopping relays E and F prepares these relays for subsequent operation. As the elevator car A nears the fifth floor, the inductor slowdown relay E reaches the inductor plate UEP for the fifth floor which completes a magnetic circuit resulting in the opening of the normally-closed contacts E1. Such opening deenergizes the speed relay V. As a result of the deenergization of the speed relay V, make contacts V1 open to introduce the resistor R1 in series with the generator field winding 17F. The resulting decrease in the output of the generator slows the elevator car A to a landing speed. Closing of break contacts V2 (Fig. 2) has no immediate effect on the system.

As the elevator car A slowly approaches the fifth floor, the stopping relay F reaches the inductor plate UFP for the fifth floor. This completes a magnetic circuit which results in opening of the normally-closed contacts F1.

In opening the contacts F 1 deenergizes the up switch U and the running relay M.

The up switch U now opens its make contacts U1 to apply the elevator brake. Contacts U2 and' U3 open to deenergize the generator field winding and the elevator car now stops accurately at the fifth floor. Opening of the make contacts U4 and U5 and closure of the break contacts U6 have no immediate effect on the operation of the system.

The running relay M opens its make contacts M1 to deenergize the relays G, E and F. The relay G opens its make contacts G1. Opening of the make contacts M2 has no immediate effect on the system operation. Make contacts M3 open to deenergize the non-interference relay 70T. This relay now starts to time out. Opening of make contacts M4 (Fig. 2) has no immediate effect on system operation.

Referring .to Fig. 2, it should be noted that as the elevator car A continues its approach toward the fifth floor, the brush dd engages the contact segment d5.

17 When the running relay drops out to close its break contacts M5, the following cancelling circuit is completed:

L1, CR1, SCRN, (15, dd, W4, M5, L2

Consequently, the car call registering relay SCR is reset. As the car comes to a stop, the brush bb passes slightly above the associated contact segment b5.

The resetting of the call registering relay SCR opens the make contacts SCRI. In addition, the break contacts 5CR2 (Fig. 3) reclose to complete an energizing circuit for the call relay 78 (Fig. 3). The make contacts 5CR3 open to interrupt the partial energization of the relays MHCR and HCR.

The call relay 73 as a result of its energization opens its break contacts 73-1 (Fig. 1). Consequently, when the non-interference relay 70T times out and recloses its break contacts 70T1 the up switch U and the running relay M can not be energized until a call is registered from one of the floors or in the elevator car A to close the contact 78-1.

Next it will be assumed that as the elevator car A was leaving the first floor in the preceding example, a prospective passenger at the second floor registered an up floor call by operation of the up floor call push button 2U (Fig. 2). Such operation energizes the up floor call registering relay ZUR which closes its contact 2UR1 to establish a holding circuit around the push button. In addition, the registering relay opens its break contacts 2UR2 in the call circuit 39 (Fig. 3) and similar contacts, such as the contact 2UR3, in the call circuits for the remaining elevator cars in the bank. Since the registration of the car call for the fifth floor in the elevator car A has deenergized the relays 78U and 78, opening of the contacts 2UR2 has no effect thereon. However, the opening of the contacts may affect the remaining elevator cars of the system. For example, the opening of the break contacts 2UR3 deenergizes the relay 78 for the car B and permits operation of such elevator car.

As the elevator car A nears the second floor, the brush 66 engages the contact segment e2 to establish the circuit:

L1, 2UR1, (22, ee, W5, MHCR3, S, EMI, L2

The resultant energization of the floor call stopping relay S results in closure of make contacts S1 (Fig. l) to en? crgize the relays G, E and F. These cooperate to stop the elevator car A at the second floor by a sequence which will be clear from the preceding discussion of the stopping of the elevator car at the fifth floor. As the elevator car stops, the engagement of the brush ff with the contact segment f2 and the closure of the break contacts V2 completes the following cancelling circuit:

L1, 2UR1, 2URN, f2, ff, W6, V2, L2

This resets the up floor call registering relay 2UR in the manner previously described. As a result of this resetting, the relay opens its contacts 2UR1 and recloses its break contacts 2UR2 (Fig. 3). Inasmuch as the contacts 5CR2 remain open, the reclosure of the contacts 2UR2 has no immediate effect on the system. However, the relay also recloses its break contacts 2UR3. If no other call is registered affecting the elevator car B, the reclosure of the contacts 2UR3 results in energization of the call relay B78.

Next it will be assumed that a prospective passenger at the fourth floor registers a down floor call by operation of the push button 4D (Fig. 2) after the elevator car A reached the fifth floor. The resultant energization of the down floor registering relay 4DR closes the make contacts 4DR1 to establish a holding circuit around the push button. In addition, the registering relay opens its break contacts 4DR2 (Fig. 3) and similar contacts for the remaining cars, such as the contacts 4DR3 for the elevator car B. The opening of-the break contacts 4DR2 deenergizes the call relay 78. This relay recloses its break contacts 78-1. The down floor registering relay 4DR further closes its make contacts 4DR4 to energize partially the relays 2CC to SCC, but these relays do not pick up. Opening of break contacts 4DR6 (Fig. 4) starts a timing out operation of the relay 4DRT. It will be assumed that the elevator car A has remained at the fifth floor for time sufficient to permit reclosure of the break contacts T1 of the non-interference relay. Consequently, the up switch U and the running relay M are energized in the manner previously described to move the car upwardly to the upper terminal floor. As the elevator car A nears the upper terminal floor, the mechanical switch 28 closes and the brush ee (Fig. 2) engages the segment e6 to complete the following energiz; ing circuit:

L1, 26, ee, W5, MHCR3, S, EMl and 28 in parallel, L2

The relay S closes its make contacts S1 (Fig. 1) to energize the relays G, E and F. These relays initiate a stopping operation of the elevator car A at the sixth floor in a manner which Will be clear from the earlier discus: sion of the stopping of the elevator car at the fifth floor. As it reaches the sixth floor, the elevator car A opens its limit switch 23 (Fig. l) to 'deenergize the up preference relay W. Since this relay closes its break contacts W2 and the break contacts U6 close as the car stops, an energizing circuit is completed for the down preferance relay X through the limit switch 24. The deenergization of the up preference relay and the energizationof the down preference relay condition the elevator car for down travel. 2

After the expiration of time suflicient to permit the non-interference relay 7 0T to time out, the break contacts 70T1 close to complete the following circuit:

L1, 7011, 78-1, X1, F2, 22 D, M, DRI, L2

The relay D upon energization closes its make contact D1 to release the elevator brake. Contacts D2 and D3 close to energize the generator field with proper polarity for down travel. Contacts D4 close to complete through the limit switch 20 and the contacts E2, an energizing circuit for the speed relay V. This relay closes its make contacts V1 to shunt the resistor R1. The elevator car A now accelerates to its full speed in the down direction. Closure of the make contacts D5 establishes a holding circuit around the contacts 70T1, 78-1, and X1. Opening of the break contacts D6 has no immediate effect on the operation of the system. The running relay M upon energization operates its contacts in the manner previously described. I

As the elevator car A nears the fourth floor, the brush gg engages the contact segment g4 (Fig. 2) to complete the following energizing circuit:

L1, 4on1, g4, gg, HCR3, X6, s, EM 1,L 2

As a result of its energization, the floor call stopping relay S closes its make contact to energize the relays G, E and F. The relay G closes its make contact to establish a holding circuit around the cont-actsSl. The continued movement of the elevator :car A brings the inductor slow down relay adjacent the plate DEP for the fourth floor and completes a magnetic circuit resulting in opening of the contacts E2. Such opening results in deenergization of the speed relay V and this relay closes its contacts V2 (Fig. 2) and opens it makes contact V1 (Fig. l) to introduce the resistor R1 in series with the generator field winding. The decrease in energization of the field winding slows the elevator car to a landing speed. The continued movement of the elevator car A at a slow speed brings the inductor stopping relay F adjacent the inductor plate DFP to open the contacts F2. Such opening deenergizes the down switch D and the running relay M. The. down switch D Opens its make contacts D1 to apply the elevator brake. Contacts D2 and D3 open to deenergize the generator field winding and the elevator car 19 stops accurately at the fourth floor. Opening of make contacts D4 and D5 and closure of break contacts D6 have no'immediate effect on the operation of the system. During the stopping operation the brush hh (Fig. 2) engages the contact segment I14 to complete the following cancelling circuit:

In resetting, the relay 4DR opens its holding contacts 4DR1. In addition, the relay recloses its break contact 4DR2 (Fig. 3) and corresponding contacts in the call circuits for the remaining elevator cars of the bank. If no other call is registered affecting the call circuit 30, the call relay 78 is energized and prevents further operation of the elevator car A. Opening of contacts 4DR4 interrupts the partial energization of the relays c to Sec. Contacts 4DR6 (Fig. 4) are assumed to reclose before the relay 4DRT has timed out.

It will be assumed that the passenger at the fourth floor enters the elevator car and operates the push button 1c (Fig. 2) to initiate movement of the elevator car to the first floor. The resultant energization of the car call registering relay 1CR closes the holding contacts 1CR1 and opens the break contacts 1CR2 (Fig. 3). Opening of the contacts 1CR2 deenergizes the call relay 78 and this relay closes its break contacts 78-1 (Fig. 1) to permit further movement of the elevator car. If sufiicient time has elapsed for the non-interference relay 70T to drop out, the break contacts 70T1 close. If the doors also are closed, an energizing circuit again is completed for the downswitch D and the running relay M. These coopcrate in the manner previously discussed to move the elevator towards the first floor.

Closure of contacts 1CR3 partially energizes the relays MHCR and HCR.

As the elevator car A nears the first floor, the brush aa (Fig. 2) engages the contact segment al to complete an energizing circuit for the car call stopping relay T. This relay closes its make contacts T1 to energize the relays G, E and F through the contacts M1. The energized relays E and F cooperate in the manner previously described to stop the elevator car A at the first floor. As the elevator car stops, the brush dd engages the contact segment d1 to complete the following cancelling circuit:

L1, 1CR1, ICRN, d1, dd, W4, M5, L2

In resetting, the relay ICR opens its holding contacts lCRl, and closes its break contacts 1CR2 (Fig. 3) to complete an energizing circuit for the call relay 78. Opening of contacts 1CR3 interrupts the partial energization of relays MHCR and HCR. The relay 78 opens its break contacts 78-1 (Fig. 1) to prevent further operation of the elevator car A until a call is registered requiring such operation.

As it reaches the lower terminal floor, the elevator car A opens thelimit switch 24 to deenergize the down preference relay. This relay closes its break contacts X2 to complete an energizing circuit for the up preference relay W as the elevator car stops at the lower terminal floor. The deenergization of the down preference relay X and the energization of the up preference relay W conditions the elevator car A for up travel.

Up-peak operation It now will be assumed that all of the elevator cars are parked at the lower terminal floor when a passenger entering the elevator car A registers a car call for the second floor and passengers register car calls in the elevator car B for the third, fourth and fifth floors. It is assumed that the switches SW2 and SW4 are open and that the switch SW3 (Fig. 3) connects the relay MHCR in series with the relay HCR. Such registrations result in opening of the break contacts 2CR2, B3CR2, B4CR2 and BSCRZ (Fig. 3) and relays 78 and B78 drop out. In addition, make contacts 2CR3, B3CR3, B4CR3 and B5CR3 (not shown in Fig. 4) close to energize the car call quota relays MHCR and HCR. It is assumed in this example that the resistors R8, etc. are so dimensioned that currents flowing through at least three resistors are required to energize the quota relay MHCR sufiiciently to pick up, and that currents flowing through at least six resistors are required to pick up the quota relay HCR.

The registration of a large number of car calls indicates the presence of a substantially high service demand. Inasmuch as each stop of the elevator car requires substantial time, it follows that the stopping of the elevator cars a number of times as required by a large number of registered car calls appreciably slows the elevator cars.

The registration of a large number of car calls at the lower terminal floor may occur, for example, during an up peak period such as the start of a business day in an office building served by the elevator system. For this reason,.it is desirable to expedite the return of the elevator car to the lower terminal floor.

If desired, the return of the elevator car further may be expedited by preventing the elevator car A from answering certain registered floor calls during its travel. For example, during the morning up peak, few up calls generally are registered by operations of the up floor call push buttons. For this reason, it is permissible in many cases to expedite the return of the elevator cars to the lower terminal floor by preventing one or more of the elevator cars from answering registered up floor calls during up travel thereof. To this end, the break contacts MHCR3 (Fig. 2) of the first quota relay MHCR open when this relay is energized to prevent energization of the floor call stopping relay during up travel of the elevator car A. Similar contacts may be employed in other cars if so desired. However, as shown, they are not provided for the elevator car B.

To expedite return of the elevator car A, it is desirable that the break contacts of the floor call relays in the call circuit 30 be shunted during such travel of the elevator car. To this end, the make contacts MI-ICR4 to MHCR8 of the quota relay MHCR shunt the break contacts of the floor call relays above the first floor in the call circuit 30. As shown, such contacts are not provided for the elevator car B.

The elevator car A proceeds upwardly in the manner previously described answering the registered car call for the second floor. As the elevator car nears the second floor, the brush kk (Fig. 3) engages the contact segment k2 to complete the following energizing circuit for the call-above relay 78U:

L1, 6CR2, MHCR4, 5CR2, MHCRS, 4CR2, MHCR6, 3CR2, MHCR7, k2, kk, W7, 78U, L2

As a result of its energization, the call-above relay closes its make contacts 78U1 (Fig. 1) to complete with the contacts MHCRI and X3 an energizing circuit for the reversal relay I which closes contacts II to energize the relays G, E and F. Under the assumed conditions, these relays G, E and F also would have been energized in the manner previously described as the elevator car A an swered the registered car call for the second floor.

In addition, the reversal relay opens its break contact J2. Inasmuch as the make contacts M2 of the running relay open as the car comes to a stop, it follows that the up preference relay W is deenergized as the elevator car stops at the fourth floor. The deenergized up preference relay closes it break contacts W2 to complete an energizing circuit for the relay X. Since the down preference relay now is energized and the up preference relay W is deenergized the elevator car A is conditioned to return to the lowerterminal floor. The operation of the system in returning the elevator car A to the lower terminal floor will be understood from the foregoing discussion. By reversing the elevator car A at the intermediate floor, the return of the elevator car to the lower terminal floor is materially expedited.

To assure prompt return of the elevator car A to the first floor, the manual switch 31 may be closed to connect the mechanical switch 32 across the push button 10 for the first floor. This mechanical switch is biased into closed condition and is cam-operated to open as the elevator car A reaches the lower terminal floor. Consequently, as soon as the car leaves the first floor the switch 32 closes to establish a parking call for the first floor.

Let it be assumed next that before the elevator car A left the first floor two additional car calls were registered by passengers therein pressing the buttons 50 and 60. This results in the energization of the relays HCR and MHCR (Fig. 3) through the make contacts CR3 and 6CR3 as well as through the make contacts 2CR3, B3CR3, B4CR3 and BSCRS. Both relays HCR and MHCR are picked up under these conditions. The effect of pickup of the relay MHCR has been discussed.

Upon picking up, the relay HCR opens its break contacts HCRI and HCRZ (Fig. 2) to prevent response of the elevator car B to all floor calls. Opening of contacts HCR3 prevents response by the elevator car A to down floor calls.

Closure of contacts HCR4 to HCR8 (Fig. 3) shunts the contacts of the fioor call registering relays for floors above the first floor. Consequently the elevator car B is conditioned to reverse when it reaches the farthest floor in the up direction for which a car call is registered.

The effect of closure of the switches SW2 and SW4 and of operation of the switch SW3 to its upper position, as viewed in Fig. 4, on the operation of the system now will be considered. When the switch SW3 is in its upper position, a shunt is connected across the poles or blades of the switch.

It again will be assumed that a passenger entering the elevator car A registers a car call for the second floor, and passengers register car calls in the elevator car B for the third, fourth and fifth floors. It will be assumed first that these passengers enter the elevator cars at a time when a balanced demand for elevator service is anticipated. Consequently, contacts CL4 of the time switch are closed and contacts GL5 of the time switch are open.

When the switch SW2 was closed, the first timing relay PUT was energized through the contacts 2CC3, 1T3 and PU1. Consequently, break contacts PUT1 are now open. As a result of the energization of the relay PU through the make contacts 2CR3, B3CR3, B4CR3 and B5CR3 (not shown in Fig. 4-), the relay PU picks up to open its break contacts PU1 and close its make contacts PU2. Opening of the break contacts PUl starts a timing out operation of the first timing relay PUT. Inasmuch as an intense demand for up service is not anticipated at this time, the contacts CL4 are closed and the relay PUT has a long time delay in dropout. As a specific example, this time delay may be of the order of 5 seconds. The closure of the make contacts PU2 completes with the break contacts 2CC3 and 1T3 and the switch SW2 an energizing circuit for the second timing relay DOT which closes its make contacts DOT 1 without immediate effect on the operation of the system.

Upon the expiration of its time delay, the relay PUT drops out to close its break contacts PUT1. This completes with the break contacts 2CC3 and IT3 an energizing circuit for the first car call quota relay MHCR, which operates in the manner previously described .to expedite elevator service in the up direction. However, because of the operation of the relay PUT, the conditions necessary to cause energization of the relay MHCR must persist for at least 5 seconds. In addition, the relay MHCR closes its make contacts MHCR9 to complete with the contacts DOTl a holding circuit around the break contacts PUT1.

When a sufficient number of car calls have been answered, the relay PU drops out to close its break contacts PUl which results in energization of the first timing relay PUT. The resultant opening of the break contacts PUT1 has no immediate effect on the operation of the system.

In addition, the make contacts PU2 open to deenergize the second timing relay DOT. Inasmuch as the contacts CLS of the time switch are open, the relay DOT has a short or negligible time delay in dropout which may be of the order of three seconds. Upon the expiration of this time delay, the relay DOT drops out to open its make contacts DOTl and deenergize the relay MHCR. The efiect of the deenergization of the relay MHCR has been discussed previously.

From the foregoing discussion, it is clear that if a number of car calls are registered at a time when no intense demand for up service is anticipated, the transfer of the system to up-peak operation is delayed, and the return of the elevator system to balanced operation is expedited. Let it be assumed next that the aforesaid passengers registered their calls at a time when an intense demand for service in the up direction was to be anticipated. Such a time may, for example, be between 7:30 A. M. and 8:00 A. M. During this period, the time switch opens its make contacts CL4 and closes its contacts CLS. This means that the time delay in dropout of the relay PUT is negligible, whereas the time delay in dropout of the relay DOT is substantial, such as a time delay of two minutes. Under these circumstances, pickup of the relay PU promptly transfers the system to up-peak operation, and when the relay PU drops out, the return of the elevator system to off-peak operation is subjected to the full delay of 2 minutes introduced by the relay DOT. Consequently, the system tends to maintain its up-peak service despite momentary decreases in the number of registered car calls.

Relays similar to the relays PU, PUT and DOT may be employed in a similar manner for controlling the energization and dropout of the relay HCR.

Down peak operation For the purpose of illustrating the gradual increase in carrying capacity in the system in the down direction as the demand for elevator service increases, it will be assumed initially that down fioor calls are registered at the second and third floors. The sequence for registerin-g such calls will be understood from the foregoing discussion. It will be recalled that as a result of registration of these floor calls the break contacts 2DR5 and 3DR6 (Fig. 4) open and the floor call timing relays ZDRT and SDRT start to time out.

in addition the down call quota relays 2CC, 3CC, 4CC and ECG all are energized through two arms of the associated parallel circuit. Such energization is sufiicient to pick up only the relay 2CC. For present purposes the switch SW1 is open and the switch SW6 connects the relay ZCC in series with the relays 3CC to SCC.

As a result of its energization the down call quota relay 2C0 closes its make contacts 2CC1 (Fig. 1) to prepare the reversal relay J for subsequent energization. Similar contacts 2CC2 associated with the reversal relay B] for the elevator car B also are enclosed. Each of the elevator cars now is conditioned during up travel to stop and reverse at the highest floor for which a call is registered provided such call is not an up floor call. For example, let it be assumed that immediately after the pick up of the down call quota relay 2CC the elevator car A is traveling up and approaches the third floor. During such approach the brush kk (Fig. 3) engages the contact segment k3. Since it is assumed that no call is registered for a floor above the third floor and that no up floor call is registered for the third floor, the fol-lowing circuit is completed:

L1, 6CR2, 6DR2, 5UR2, 5CR2, 5DR2, 4UR2, 4CR2, 4DR2, 3UR2, k3, kk, W7, 78U, L2 Since the call above relay 78U now is energized, the make contact 78U1 (Fig. l) closes to complete with the contacts 2CC1 and X3 an energizing circuit for the reversing relay 1. This energized relay then operates in the manner previously discussed to stop and reverse the elevator car A at the third floor. During its return to the 23 lower terminal floor, the elevator car A accepts passengers from the third and second floors in a manner which will be understood from the preceding discussion.

When it picks up, the down call quota relay ZCC also opens its break contacts 2CC3 to prevent energization of the car call quota relays MHCR and HCR.

Next it will be assumed that a down floor call is registered only for the second floor but that this floor call has remained unanswered for a time suflicient to permit dropout of the floor call timing relay ZDRT (Fig. 4). It will be recalled that this timing relay starts to time out as soon as registration of a call at the second floor opens the break contacts 2DR5.

Upon dropping out the floor call timing relay ZDRT closes its break contacts 2DRT1 (Fig. 3) to energize the timed call relays IT to 4T. However, the energization of these relays through only one arm of the associated parallel circuit is sufficient to pick up only the relay 1T.

Upon pickup the relay 1T closes its make conetacts 1T1 and 1T2 (Fig. 1) to prepare the reversal relays for subsequent energization. Consequently, the effect of the closure of the contacts 1T1 and 1T2 is similar to that ol the closure of the contacts 2CC1 and 2CC2 which has just been described.

In addition the timed call relay 1T opens its break contacts 1T3 (Fig. 3) to prevent energization of the car call quota relays HCR and MHCR.

From the foregoing discussion it is clear that the pickup of either the relay ZCC or the relay 1T results in an increase in the carrying capacity of the elevator system in the down direction.

Next it will be assumed that down floor calls are registered for the second, third and fourth floors. As a result of such registrations,- the break contacts 2DR5, 3DR6 and 4DR6 (Fig. 4) open to start timing out operations of the floor call timing relays 2DRT, 3DRT and 4DRT.

The registration of these three calls also results in closure of the make contacts 2DR4, 3DR4 and 4DR4 (Fig. 3) to energize the down call quota relays 2CC, 3CC, 4CC and SCC. However, the energization applied through three arms of the parallel circuits is sufiicient to pick up only the relays 2CC and 3CC. The relay ZCC operates in the manner previously discussed to condition the elevator cars to reverse when traveling up at the highest floor for which a call is registered unless the call is an up floor call. The relay 3CC opens its break contacts 3CC1 (Fig. 2) to prevent the elevator car B from responding to up floor calls. Also contacts 3CC2 close to energize the relay USE. The relay USE closes its contacts USEl to USE4 for the purpose of shunting contacts of the up floor-call registering relays in the circuit B30 for the elevator car B. The elevator car B now is set to reverse at the highest of the car calls and down floor calls. This further expedites elevator service in the down direction.

Next let it be assuemd that two down floor calls are registered for the second and third floors and that these calls have beeen rgistered for a time sutficient to permit dropout of the floor call timing relays ZDRT and 3DRT (Fig. 4). As a result of such dropouts these relays close their break contacts ZDRTI and 3DRT1 (Fig. 4) to energize the timed call relays IT to 4T. However, such energization through two of the parallel arms associated with the relays suffices to pick up only the relays IT and 2T. The relay 1T operates in the manner previously described to condition the elevator cars to reverse when traveling up at the highest floor for which a call is registered provided such call is not an up floor call. The relay 2T opens its break contacts 2T1 (Fig. 2) to prevent the elevator car B from responding to up floor calls. In this way service in the down direction is expedited.

For the next operation to be discussed it will be assumed that down floor calls are registered for the second, third, fourth and fifth floors. As a result of such registrations 24 make contacts 2DR4, 3D4R, 4DR4 and 5DR4 (Fig. 3} close to energize the down call quota relays ZCC, 3CC, 4CC and SCC through four arms of the associated parallel circuit. Such energization suffices to pick up the relays 2CC, 3CC and 4CC. The operation of the relays ZCC and 3CC has been discussed above.

Upon picking up the down call quota, relay 4CC closes its make contacts 4CC1 to energize the first down service demand relay DSE. This relay further expedites travel in the desired direction as by dividing the floors into groups or zones and assigning a separate car or group of cars to each zone of floors. Such zoning during down peak periods is well known in the art.

Had only three down floor calls been registered and had all of the three calls timed out, the timed call relays IT to 41" (Fig. 3) would have been energized through three arms of the parallel circuit. Such energization would have sufiiced to pick up the relays 1T, 2T and ST. The relays IT and 2T would operate in the manner previously described. The pickup of the relay 3T would result in closure of the make contacts 3T1 to energize the first down service demand relay. Consequently, the energization of either of the relays ST or 4CC results in a substantial increase in the carrying capacity of the elevator system in the down direction.

For the next condition to be examined it will be assumed that down floor calls are registered for the second, third, fourth, fifth and sixth floors. Under such circumstances the down call quota relays 2CC to SCC will be energized through all of the parallel arms associated therewith and all of the quota relays will be picked up. Inasmuch as the eifect of pickups of the relays ZCC, 3CC and 4CC already has been considered, consideration need be given at this point only to the effect of the pickup of the quota relay SCC.

As a result of its pickup, the quota relay SCC closes its make contacts 5CC1 to energize the second down service demand relay EM. It should be noted that this relay also may be energized as a result of closure of the make contacts 4T1. Consequently, a similar result is obtained it four down floor calls have been registered for a time sufficient to permit dropout of four of the floor call timing relays 2DRT to 6DRT. Under such circumstances the timed call relays IT to 4T (Fig. 4) would be energized through four arms of the associated parallel circuit and all of the timed call relays would be picked up. As before noted, the pickup of the relay 4T results in closure of the make contacts 4T1 to energize the second down service demand relay EM.

Pickup of the second down service demand EM results in opening of the break contacts EMI and EM2 to prevent energization of the floor call stopping relays S and BS. The stopping of the elevator cars during down travel now is controlled by the timed floor call stopping relays SE and BSE (Fig. 4). An elevator car now stops in response to a down floor call only if the down floor call has been registered for more than a predetermined time. Inasmuch as passengers tend to accumulate during the time required to make a down floor call effective for stopping the elevator car, it follows each stop of an elevator car in response to such a call results in the loading of a larger number of passengers and an increase in the capacity of the elevator system to carry passengers in the down direction.

To illustrate the stopping operation under these conditions, it will be assumed that the elevator car A is traveling down towards the third floor and that a down floor call for the third floor has been registered for a time sufficient to permit the floor call timing relay 3DRT to time out and close it breaks contacts 3DRT2. As the elevator car A approaches the third floor, the brush nn engages the contact segment n3 to complete the following energizing circuit:

L1, EM11, 3DRT, n3, nn, SE, X8, L2 

